Heater



FIG. 1 is a left-front perspective view of a heater showing our new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a left side elevation view thereof;

FIG. 5 is a right side elevation view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The elements shown by broken lines on the FIGS. 3 and 7 and the recessed parts shown by broken lines on FIG. 5 are for the illustrative purposes only, form no part of the claimed design. 

CLAIM The ornamental design for a heater, as shown and described. 